The operator of a winch or hoist, either on a crane or mounted on a truck cannot always see the load that is being moved which can present a hazard. When an operator is raising or lowering a load, the operator is usually guided by an additional person giving directions either by radio or hand signals. Also known is a device of this type for indicating to the operator when the cable drum of the winch is rotating in either direction to move the load. The device for this can be mechanical or electrical.
It is typical of the present art that a drum rotation indicator is external to the winch and driven by a wheel that rides on a flange of the drum or is shaft-driven to an external output device. Both of these types of systems are susceptible to mechanical or environmental damage.
U.S. Pat. No. 3,922,605 shows an electrical winch drum rotation-indication system with a stepper motor driven from the winch drum to drive a tactile indicator for the operator.
U.S. Pat. No. 4,098,221 shows a drum rotation indicator with a readout plunger, that is located conveniently for the operator's hand. The plunger is moved linearly, in response to rotation of the drum, with sufficient force to give a positive feel, to the operator's hand.
U.S. Pat. No. 4,809,857 shows a drum rotation indicator with a rate generator connected to the winch which develops electrical pulses having a frequency proportional to winch rotational speed. A solenoid having a movable plunger is mounted in the cab of the crane where the vibration of the plunger can be sensed by a crane operator.
The following references are of general interest for showing cable drum indicators. U.S. Pat. No. 2,745,633; U.S. Pat. No. 2,776,814; U.S. Pat. No. 3,742,307; U.S. Pat. No. 3,750,130; U.S. Pat. No. 3,883,859; U.S. Pat. No. 4,156,467; U.S. Pat. No. 4,342,028; JP401043498.